1. Technical Field
This invention relates to a vehicle illumination lamp using light-emitting elements (such as light-emitting diodes) as a light source.
2. Background
In the related art, vehicle illumination lamps using a light-emitting diode as a light source have been extensively used.
JP-A-2003-317513 discloses a vehicle illumination lamp including a plurality of lamp units each having a light-emitting diode as a light source. Each lamp unit of this vehicle illumination lamp is designed such that light from the light-emitting diode is reflected by a reflector, and is irradiated forward via a projection lens.
JP-A-2001-266620 discloses a vehicle illumination lamp in which light from a plurality of light-emitting diodes arranged in a matrix-like pattern is irradiated forward via a projection lens.
When the vehicle illumination lamp comprises a single lamp unit having a single light-emitting diode as a light source, it is difficult to secure a sufficient amount of irradiated light. However, when a vehicle illumination lamp comprises a plurality of such lamp units as disclosed in JP-A-2003-317513, or includes a plurality of light-emitting diodes serving as a light source as disclosed in JP-A-2001-266620, a sufficient amount of irradiated light can be secured.
In the vehicle illumination lamp described in JP-A-2003-317513, however, there is a problem in that an optical axis of the projection lens of each lamp unit needs to be accurately positioned to precisely effect light irradiation control. As a result, the lamp is complicated in structure.
On the other hand, in the vehicle illumination lamp described in JP-A-2001-266620, direct light from each light-emitting diode is incident on the projection lens. Therefore, there is a problem in that the rate of utilization of light flux from the light-emitting diode is considerably low.